In a related art technique, a backup storage device for a storage device is configured to be on standby in an operative state, and if the storage device malfunctions, the backup storage device is used instead of the storage device. In another related art technique, a verification process is periodically performed to verify whether the backup storage device is in a normal function state and thus to guarantee the reliability of the backup storage device.
In yet another related art technique, a central processing unit (CPU) counts the number of accesses to a memory block. If the number of accesses exceeds a predetermined value, the CPU reduces the number of memory patrols, each of which is periodically performed to detect an error of the memory block and to correct the error. In another related art technique, if a condition, based on at least one of an access count to a cell of a flash memory device, and an amount of time that has elapsed since storage of information on the flash memory device is satisfied, a scan operation is performed to detect an error in the information stored on the flash memory device. In another related art technique, depending on the frequency of occurrence of an input and output operation related to a command through a channel during a past fixed period of time determined by a diagnosis control timer and a diagnosis control counter, a determination as to whether a read diagnosis of a disk device is enabled is performed, and the number of read target tracks is determined. The read diagnosis is thus performed during an idle time period in the input and output operation.
The related art techniques are disclosed in Japanese Laid-open Patent Publication Nos. 2014-059821, 5-74059, and Japanese National Publication of International Patent Application No. 2010-537314.